001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 */
019
020package org.apache.isis.core.progmodel.facets.param.defaults.fromtype;
021
022import org.apache.isis.core.metamodel.facetapi.FacetUtil;
023import org.apache.isis.core.metamodel.facetapi.FeatureType;
024import org.apache.isis.core.metamodel.facets.FacetFactoryAbstract;
025import org.apache.isis.core.metamodel.facets.actions.defaults.ActionDefaultsFacet;
026import org.apache.isis.core.metamodel.spec.ObjectSpecification;
027import org.apache.isis.core.progmodel.facets.object.defaults.DefaultedFacet;
028
029public class ParameterDefaultDerivedFromTypeFacetFactory extends FacetFactoryAbstract {
030
031    public ParameterDefaultDerivedFromTypeFacetFactory() {
032        super(FeatureType.PARAMETERS_ONLY);
033    }
034
035    /**
036     * If there is a {@link DefaultedFacet} on any of the action's parameter
037     * types, then installs a {@link ActionDefaultsFacet} for the action.
038     */
039    @Override
040    public void processParams(final ProcessParameterContext processParameterContext) {
041        // don't overwrite any defaults already picked up
042        if (processParameterContext.getFacetHolder().getFacet(ActionDefaultsFacet.class) != null) {
043            return;
044        }
045
046        // try to infer defaults from any of the parameter's underlying types
047        final Class<?>[] parameterTypes = processParameterContext.getMethod().getParameterTypes();
048        final DefaultedFacet[] parameterTypeDefaultedFacets = new DefaultedFacet[parameterTypes.length];
049        boolean hasAtLeastOneDefault = false;
050        for (int i = 0; i < parameterTypes.length; i++) {
051            final Class<?> paramType = parameterTypes[i];
052            parameterTypeDefaultedFacets[i] = getDefaultedFacet(paramType);
053            hasAtLeastOneDefault = hasAtLeastOneDefault | (parameterTypeDefaultedFacets[i] != null);
054        }
055        if (hasAtLeastOneDefault) {
056            FacetUtil.addFacet(new ActionParameterDefaultFacetDerivedFromTypeFacets(parameterTypeDefaultedFacets, processParameterContext.getFacetHolder()));
057        }
058    }
059
060    private DefaultedFacet getDefaultedFacet(final Class<?> paramType) {
061        final ObjectSpecification paramTypeSpec = getSpecificationLoader().loadSpecification(paramType);
062        return paramTypeSpec.getFacet(DefaultedFacet.class);
063    }
064
065}